As applications such as big data and cloud computing constantly develop, data center and mobile bearer markets and the like grow rapidly. When a multimode optical fiber is used, a relatively low cost laser may be used, which has an advantage of low system costs. Therefore, the multimode optical fiber is highly competitive in short-range transmission scenarios such as data center transmission and mobile bearer transmission
In addition, as a data center and a mobile bearer network grow in scale, to control an optical fiber scale, a requirement for a single-fiber capacity is increasing. In the prior art, a parallel system solution is mainly used. For example, in a parallel system that supports 40 Gbps, 100 Gbps, and 400 Gbps, 4 pairs of 10-Gbps transceivers, 10 pairs of 10-Gbps transceivers, and 16 pairs of 25-Gbps transceivers are respectively used to carry optical signals in parallel optical fibers respectively including 4, 10, and 16 optical fibers, to implement 40-Gbps, 100-Gbps, and 400-Gbps network transmission. However, such a method is combining multiple optical fibers to implement large-capacity data transmission, without increasing a transmission capacity of a single optical fiber. As a network capacity and a network rate increase, how to increase the transmission capacity of the single optical fiber is a problem that needs to be urgently resolved.